WordReference Random House Unabridged Dictionary of American English © 2025
ac′tive sun′, [Astron.]
- Astronomythe sun at a maximum of solar activity, occurring every 11 years.
- Astronomysolar activity, superimposed on an unchanging background. Cf. quiet sun, solar cycle.
- 1975–80
'active sun' also found in these entries (note: many are not synonyms or translations):